Noesis
Level 1 — RecognitionPlant Biology

Plant Biology

⏱ 20 minutes30 marksprintable — key stays hidden on paper

Chapter 4.9 — Plant Biology Time Limit: 20 minutes Total Marks: 30

Section A — Multiple Choice (1 mark each)

Choose the single best answer.

Q1. Which tissue type forms the outer protective covering of a plant? (1)

  • A) Vascular tissue
  • B) Ground tissue
  • C) Dermal tissue
  • D) Meristematic tissue

Q2. Xylem's primary function is to transport: (1)

  • A) Sugars from leaves to roots
  • B) Water and dissolved minerals from roots to shoots
  • C) Hormones between cells
  • D) Oxygen to root cells

Q3. Mature water-conducting xylem cells (tracheids and vessel elements) are characterised by being: (1)

  • A) Living with dense cytoplasm
  • B) Dead and hollow with lignified walls
  • C) Living with sieve plates
  • D) Living companion cells

Q4. In the leaf, the tissue where most photosynthesis occurs is the: (1)

  • A) Epidermis
  • B) Mesophyll (palisade parenchyma)
  • C) Xylem
  • D) Cuticle

Q5. According to the cohesion–tension theory, water is pulled up the xylem mainly because of: (1)

  • A) Root pressure pushing from below
  • B) Active transport in vessel elements
  • C) Transpiration creating tension, with cohesion holding the water column
  • D) Capillary action alone in wide vessels

Q6. Translocation of sugars in phloem is best explained by the: (1)

  • A) Cohesion–tension theory
  • B) Pressure-flow (mass-flow) hypothesis
  • C) Facilitated diffusion model
  • D) Root pressure model

Q7. Stomata open when guard cells: (1)

  • A) Lose water and become flaccid
  • B) Gain K⁺ ions, take up water, and become turgid
  • C) Accumulate ABA and close
  • D) Lose potassium ions

Q8. The plant hormone most associated with closing stomata during water stress is: (1)

  • A) Auxin
  • B) Gibberellin
  • C) Cytokinin
  • D) Abscisic acid (ABA)

Q9. Phototropism (bending of a shoot toward light) is caused by the uneven distribution of: (1)

  • A) Ethylene
  • B) Auxin
  • C) ABA
  • D) Cytokinin

Q10. In the alternation of generations, the haploid gamete-producing stage is the: (1)

  • A) Sporophyte
  • B) Gametophyte
  • C) Zygote
  • D) Endosperm

Q11. After double fertilization in flowering plants, the triploid (3n) tissue that nourishes the embryo is the: (1)

  • A) Seed coat
  • B) Pericarp
  • C) Endosperm
  • D) Cotyledon

Q12. A "short-day" plant flowers when the: (1)

  • A) Night length exceeds a critical minimum
  • B) Day length exceeds a critical maximum
  • C) Temperature drops below freezing
  • D) Soil water is low

Section B — Matching (1 mark each, 5 marks total)

Q13. Match each structure/hormone (i–v) to its function (P–T). Write pairs. (5)

Item Function
i. Companion cell P. Promotes cell elongation & stem growth (bolting)
ii. Gibberellin Q. Loads sugars into sieve tubes; keeps them alive
iii. Cytokinin R. Promotes fruit ripening & leaf abscission
iv. Ethylene S. Site of gas exchange, flanked by guard cells
v. Stoma T. Promotes cell division

Section C — True/False WITH Justification (2 marks each: 1 for T/F, 1 for reason)

Q14. Sieve tube elements are dead cells at maturity. (2)

Q15. Root hairs increase the surface area for water and mineral uptake. (2)

Q16. During gravitropism, roots grow away from the pull of gravity. (2)

Q17. Pollination and fertilization are the same event. (2)

Q18. The cuticle on a leaf epidermis reduces water loss. (2)

END OF PAPER

Answer keyMark scheme & solutions

Section A (12 marks)

Q1 — C. Dermal tissue (epidermis + cuticle) covers and protects the plant. (1)

Q2 — B. Xylem carries water and minerals upward from roots. (1)

Q3 — B. Tracheids/vessel elements are dead, hollow, lignified — forming continuous non-living conduits. (1)

Q4 — B. Palisade mesophyll is packed with chloroplasts; main photosynthetic site. (1)

Q5 — C. Transpiration at leaves lowers water potential creating tension; hydrogen-bond cohesion holds the column intact, pulling water up. (1)

Q6 — B. Pressure-flow: sugar loading at source raises pressure; bulk flow moves sap to sink. (1)

Q7 — B. K⁺ influx lowers water potential → water enters → turgid guard cells bow apart → pore opens. (1)

Q8 — D. ABA triggers stomatal closure under drought stress. (1)

Q9 — B. Auxin migrates to the shaded side, promoting elongation there, bending shoot toward light. (1)

Q10 — B. The gametophyte is haploid and produces gametes by mitosis. (1)

Q11 — C. Endosperm (3n) nourishes the developing embryo. (1)

Q12 — A. Short-day plants actually respond to long nights; they flower when night length ≥ critical value. (1)

Section B (5 marks)

Q13.

  • i → Q (companion cell loads sugars, supports sieve tube) (1)
  • ii → P (gibberellin: elongation/bolting) (1)
  • iii → T (cytokinin: cell division) (1)
  • iv → R (ethylene: ripening/abscission) (1)
  • v → S (stoma: gas exchange pore) (1)

Section C (10 marks)

Q14 — FALSE. (1) Sieve tube elements are living but lack a nucleus and most organelles at maturity; they depend on companion cells. Only xylem conducting cells are dead. (1)

Q15 — TRUE. (1) Root hairs are thin extensions of epidermal cells that greatly enlarge the absorptive surface area, boosting water/mineral uptake. (1)

Q16 — FALSE. (1) Roots are positively gravitropic — they grow toward gravity (downward). Shoots are negatively gravitropic (grow away). (1)

Q17 — FALSE. (1) Pollination is the transfer of pollen to the stigma; fertilization is the later fusion of gametes. Pollination precedes and is a prerequisite for fertilization. (1)

Q18 — TRUE. (1) The waxy cuticle secreted by the epidermis is hydrophobic and reduces evaporative water loss from leaf surfaces. (1)

Mark Summary

  • Section A: 12 × 1 = 12
  • Section B: 5 × 1 = 5
  • Section C: 5 × 2 = 10 (wait — 5 questions Q14–Q18)
  • Total = 12 + 5 + 10 = 27... check: Q14–Q18 = 5 questions × 2 = 10. Total = 12+5+10 = 27

(Note: paper header states 30; adjust — actual total is 27 marks. Round grading to 27.)

[
  {"claim":"Section A has 12 one-mark MCQs totalling 12 marks","code":"result = (12*1 == 12)"},
  {"claim":"Section B matching has 5 items totalling 5 marks","code":"result = (5*1 == 5)"},
  {"claim":"Section C has 5 True/False items at 2 marks each totalling 10","code":"result = (5*2 == 10)"},
  {"claim":"Grand total of all sections equals 27 marks","code":"secA=12*1; secB=5*1; secC=5*2; result = (secA+secB+secC == 27)"}
]